Reducing Noise from Offshore Wind Piling: A Pilot

Introduction<br/>Underwater noise is increasing in the marine environment. A key area of concern is impulsive noise which can be generated from a range of activities including piling during the installation of offshore wind turbine foundations. Without mitigation, mid-frequency sound, such as from impact piling, has been shown to cause permanent hearing loss, tissue damage and lethal injury to marine mammals. The sound can also result in disturbance effects, such as disruption of foraging and potential impacts to breeding, communication and navigation. This can be potentially more harmful at the population level as it can impact a larger number of marine mammals. Fish have also been shown to have lethal and sub-lethal effects from impulsive sounds. It is thought that piling can also cause physiological impacts to eggs and larvae as these life stages contain air sacs. Other impacts such as poor body condition post hatching could occur, in addition to behavioural impacts that can affect the population level. For example, if piling activity is to take place close to a known spawning bed or ground for herring during the key spawning period, the behaviour of the spawning herring could potentially be disturbed, leading to spawning taking place in less suitable locations, or not at all. Mackerel have demonstrated changes in their shoaling behaviour when exposed to piling noise and Atlantic cod have been shown to have delayed migrations to spawning grounds when exposed to pile driving noise